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Monthly Archives for November 2012

The growing prevalance of highly-resistant bacterial strains may be one of the key public health issues of this century. What is important to note is that most, if not all, of our current antibiotics are based on defense mechanisms that already exist in nature. The converse is also true: most bacteria already have genes that will confer some resistance to these defenses and our use (overuse?) of antibiotics derived from these defenses has selected for strains of bacteria that express these resistant genes. Researchers are currently measuring the cell membranes of bacteria to understand how to design better antibiotics that can treat infections by antibiotic-resistant bacteria. Some of this work was recently highlighted on Phys.org

Think about the last time you got an antibiotic. Did it end with -cillin? (Penicillin, methicillin, ampicillin, etc.) These are common class of molecules that were derived originally from the Penicillium mold. The chemistry they use to do their business is all largely the same; the primary differences between them are in the little bits attached to the core of the molecule that helps it get to where its supposed to be.

Did your antibiotic begin with Cef- or Ceph-? (Cephalosporin, Cefotaxim, etc.) These molecules have the same business end as the -cillins, but are derived from a different fungus.

What about -cycline (Tetracycline, doxycycline, etc.) or -mycin (Vancomycin, neomycin?) These are all derived from the Streptomyces genus of bacteria, many species of which are common soil bacteria. The chemistry of these antibiotics is completely different from the penicillin classes or cephalosporin classes, which is one reason why they are often used as the “last lines of defense.”

What’s important and exciting about the cell membrane studies described in the link is that they hold the promise of helping us to develop antibiotics that are not based on natural compounds, which could likely make it more difficult or at least slower for pathogenic bacteria to develop a resistance to them.

It is interesting to me that over the recorded history of humankind, we have actively and aggressively intervened in the genetics of every kingdom of life to adapt them to our benefit. Every kingdom, that is, except Bacteria. In the case of the bacteria, we have done the opposite – largely adapting them to become less beneficial, and most of that intervention has been in the last century. There are lessons to be taken from this.